Scott and Bailey
ITV1

The new ITV cop drama Scott and Bailey (Sundays, 9pm) is unexpectedly good, and here's why. It feels authentic. This isn't just down to all the police procedural stuff (the series was co-created by Diane Taylor, who has a 30-year career in the police force behind her). It's in the dialogue, too. In part one (29 May), DC Rachel Bailey (Suranne Jones) turned up at the flat of Nick Savage (Rupert Graves), a smooth barrister who had recently dumped her. She wanted to know why. Was he bored with her? No. Savage told her first that she drank too much, and then that he was perturbed that she sometimes left for work without having had a shower.

The scene was comical and nasty at the same time - his distaste, her slightly flustered shame at his distaste - and even though we later discovered that Savage has a wife, to whom he had discreetly returned, that did not even remotely erode its authenticity for me. Some men do find women, their bodies and their smells, rather hard to cope with. I expect that Savage's wife, having no grisly murders to investigate, smells strongly of Crabtree & Evelyn lavender shower gel.

Who wrote this dialogue? Perhaps you won't be surprised to hear that it was Sally Wainwright. I love Wainwright's writing: it's sparky but somehow truthful, and she takes seemingly crazy risks in her work, merrily turning housewives into prime ministers (The Amazing Mrs Pritchard) and secret millionaires (At Home With the Braithwaites).

On the surface of it, this show is more conservative fare: as the Radio Times keeps telling us, essentially it's Cagney and Lacey in Manchester (Bailey's partner, DC Janet Scott, is played by the ever-brilliant Lesley Sharp). Both cops are overworked, and while Bailey is single and miserable about it, Scott has children and a husband whom she must sometimes neglect, given her hours. But you can also see Wainwright's touches everywhere.

In some other writer's hands, for instance, these two women would have a male DI - a fat, blokeish and difficult fellow who would leave them rolling their eyes behind his back. But here they have DI Gill Murray (Amelia Bullmore), a slightly comic character. In one scene, we saw her at her desk on the telephone. She was telling one of her children to photograph his homework on his mobile and text it to her.

You feel Wainwright's hand, too, in the backstories. Bailey has now decided that she requires "compensation" from Savage in the form of the bachelor flat he lived in during his separation from his wife. This is blackmail of sorts, but she is really going for it, turning up at the marital home unexpectedly, scaring the pants off him. A trailer at the end of the first programme showed that next she is going to demand something even bigger from him (well, not literally): his sperm.

Bailey is, as they say, seriously out there - and yet her skills as a cop cannot be faulted. When she is in the business of extracting a confession, it's like watching a poacher gently tickle a prize salmon's belly. How far can she go? We shall see. For my part, I don't blame her for going nuts. Who, after all, would want to be dumped by Rupert Graves? (I have only to think of his lovely performance as Jolyon in The Forsyte Saga to go all Chivers jelly.) But Wainwright will have had to balance her writerly desire for a certain kind of craziness with ITV's desire to have a hit series it can recommission (this has long-running written all over it, though whether or not Sharp would be up for that - she can hardly be short of work - is surely questionable).

Is Peter Fincham, the BBC executive who now runs the ITV network, pleased with Scott and Bailey? He should be, though the peculiar thing is that, so far as he is concerned, it's just one of many equally good shows. Daybreak is still unfathomably bad and, slowly but surely, I am coming to despise its presenters. Elsewhere, however, something truly remarkable is happening at ITV. I have this comforting, back-to-the-future feeling every time I switch over to it. Fincham and his colleagues are making the popular respectable again - and I, for one, couldn't be happier about that.